The Third Manifesto
The Third Manifesto (1995) is Christopher J. Date's and Hugh Darwen's proposal for future database management systems, a response to two earlier Manifestos with the same purpose. The theme of the manifestos is how to avoid the 'object-relational impedance mismatch' between object-oriented programming languages and relational database management systems. The Third Manifesto proposes to maintain the relational model for databases and to support objects as user-defined types.
A major theme of the manifesto is to explain how the inadequacies of existing relational database management systems are not shortcomings of the relational database model per se, but rather, of implementation decisions in those systems, and of the SQL query language that most of these systems use.
The manifesto describes an alternative to SQL, named D. D is a specification of desirable characteristics of a database language, rather than a specific syntax or grammar. As such, it describes a family of languages rather than any particular language. However, as an example, a particular member of the hypothetical D "family" called Tutorial D is described in detail, including significant portions of its grammar.
Several partial implementations of D exist, including:
- Alphora Dataphor, an open source product which implements D atop SQL databases.
- Rel, an open source implementation of Tutorial D in Java.
- Muldis Rosetta (Muldis D), an open source implementation in Perl
- Darwen, Hugh; Date, C. J. (March 1995). "The third manifesto" (PostScript). ACM SIGMOD Record (New York, NY, USA: ACM Press) 24 (1): 39–49. doi:10.1145/202660.202667. ISSN 0163-5808.
- Date, C. J. (August 1998). "Preview of The Third Manifesto". Database Programming & Design (San Francisco, CA: Miller Freeman Publications) 11 (8): 67. ISSN 0895-4518. OCLC 89297479. Retrieved 2007-06-18.
- Date, C. J.; Darwen, Hugh (1998). Foundation for object/relational databases: the third manifesto: a detailed study of the impact of objects and type theory on the relational model of data including a comprehensive proposal for type inheritance (1st ed.). Reading, MA: Addison-Wesley. xxi, 496. ISBN 0-201-30978-5. LCCN 98010364. OCLC 38431501. LCC QA76.9.D3 D15994 1998.
- Date, C. J.; Darwen, Hugh (2000). Foundation for future database systems: the third manifesto: a detailed study of the impact of type theory on the relational model of data, including a comprehensive model of type inheritance (2nd ed.). Reading, MA: Addison-Wesley Professional. xxiii, 547. ISBN 0-201-70928-7. LCCN 00035527. OCLC 43662285. LCC QA76.9.D3 D3683 2000.
- Date, C. J.; Darwen, Hugh (2006). Databases, types and the relational model: the third manifesto (3rd ed.). Reading, MA: Addison-Wesley. p. 572. ISBN 0-321-39942-0. OCLC 70044091.